WO 2009/144239 describes a device for metering and discharging accurately measured amounts of powder material from a container storing the powder material, particularly for the preparation of beverages. The device comprises:    a fixed body comprising at least a disc presenting a single pierced aperture,    a rotary top disc disposed on the top of the fixed body and presenting a taking out pierced aperture,    a rotary bottom disc disposed on the bottom of the fixed body and presenting a discharging pierced aperture,    a rotary shaft connecting the bottom disc and the top disc,wherein in the stand-by position of the device the metered pierced aperture is empty and closed to the atmosphere.
The top side of the metering and discharging device cooperates with a storing powder container and the bottom side cooperates with a mixing chamber so that a beverage can be prepared from the metered dose of powder and a dose of diluent. The storing powder container can be a simple container attached to the top side of the metering and discharging device. This container can also present specific functions like the container illustrated in WO 2009/000836 which avoids a refilling with non desirable powders. This container is adapted to work with a machine comprising a dosing unit such as described in WO 2009/144239.
One problem of such metering and discharging devices is that they are usually attached to one container containing a specific powder and that the powder inside the container cannot be changed before the container is totally empty because the container is a part of the machine. Consequently when the device is the metering and discharging powder device of a machine preparing beverages, only one type of beverage can be produced in the period during which the container is filled and until it is emptied. Then there is a need for a system of a metering and discharging powder device and a compatible container in which the container can be detached from the metering and discharging powder device even if it is not empty. It would enable the production of different beverages from the same machine even if the container is not empty: the consumer would have the possibility to change the container cooperating with the metering and discharging powder device depending on the nature of the beverage he would like to produce.
The present invention aims at solving the above problem.